A prior system for setting liner hangers is illustrated in FIG. 1 and 2. Such a typical assembly would involve a set shoe 10, a landing collar 12, and a liner 14. At the upper end of the liner string is a liner hanger 16, and above the liner hanger 16 is a packer 18. The packer 18 is actuated to contact the casing, illustrated schematically by dashed line 20. The liner hanger 16 and the packer 18 are ultimately secured to the casing 20 to complete the connection. Connected to the packer 18 is a honed bore 22. The assembly of FIG. 1 is insertable into honed bore 22 shown in FIG. 2. The liner hanger 16 is settable using hydraulic cylinder 24, while the packer 18 is settable with packer setting assembly 28. The particular system illustrated in FIGS. 1 and 2 further included a packer setting assembly 28, which has a plurality of spring-loaded dogs 30. Above the packer setting assembly 28 was a junk cover 32. A lift nipple 34 was at the top of the setting string and used for connection from the surface for manipulation of the setting tool assembly illustrated in FIG. 1 when inserted into the polished bore 22 illustrated in FIG. 2.
The setting assembly shown in FIG. 1 is inserted into the wellbore with the liner assembly shown in FIG. 2 in a fully assembled condition. The junk cover 32 and packer setting assembly 28 are at that time disposed within polished bore 22. Various preparatory activities for cementing may be occurring in the wellbore and the junk cover 32 is disposed in polished bore 22 to keep debris from entering polished bore 22. Thereafter, prior to initiating the cementing operations, it is necessary to know that the setting string shown in FIG. 1 can be readily manipulated with respect to the liner string shown in FIG. 2 after the liner hanger 16 has been set against casing 20. Part of the procedure in the design of FIGS. 1 and 2 has been to raise the setting string shown in FIG. 1 so that the junk cover 32 comes out of polished bore 22 and the dogs 30 exit polished bore 22 so that they can spring outwardly and use end 36 as a support point for packer setting assembly 28. When that occurs, the packer 18 can be set. Several problems occur because of this procedure. First, by taking the junk cover 32 out of polished bore 22, the end 36 of polished bore 22 is opened up to the wellbore, thus making it possible for debris to enter polished bore 22. Another scenario that could lead to the junk cover 32 coming out of polished bore 22 was the pressure placed on setting string in FIG. 1. During the cementing process, upward reaction forces can be exerted on the setting tool assembly shown in FIG. 1 to the point where during cementing, the junk cover 32 exits bore 22, thus allowing foreign matter to get into polished bore 22. The debris could trap the setting tool assembly in the packer, causing expensive retrieving (fishing) and possibly well abandonment. The problem with foreign matter in polished bore 22 is that subsequent operations after the setting assembly of FIG. 1 is removed are necessary. Those subsequent operations depend on being able to obtain a sealing engagement with polished bore 22, which is connected to the packer 18. Additionally, the packer 18 may be a retrievable type which will require subsequent operation of internal components which may become inoperative if fouled with debris. Thus, the removal of the junk cover, for whatever reason, from the bore 22 gives debris a chance to enter bore 22 and foul or plug it or, alternatively, to scratch the polished surface, thereby making it difficult and in some cases impossible to obtain a sealing contact with bore 22 for subsequent operations with equipment thereafter lowered into bore 22. Another factor that adversely affected the ability of subsequent equipment lowered into bore 22 to seal in the bore was the upward movement of the setting string shown in FIG. 1, which resulted in the spring-biased dogs 30 riding against polished bore 22. This upward and/or rotational movement of the setting string of FIG. 1 and dragging of the dogs 30 created longitudinal and/or spiral scratches, which also potentially adversely affected the ability of seals to seal against bore 22 when subsequently stabbed into the packer 18.
Accordingly, it was desirable to create a system where polished bores such as 22 could be protected and particularly in cases where, as illustrated in FIGS. 1 and 2, a liner assembly is to be placed in a wellbore in combination with an external packer, such as packer 18. It was determined to be disadvantageous to provide a sealing contact between the junk cover 32 and the bore 22. Pressure build-up could adversely affect the structure of bore 22 and misshape it to the point of precluding subsequent operations or a subsequent sealing contact therewith.
In a different context of downhole operations, junk covers with seals have been attempted to eliminate the entry of debris. A paper presented at the 1994 Offshore Technology Conference and reprinted in the Sep. 12, 1994, issue of the Oil & Gas Journal, entitled "Floating Junk Bonnet Protects Liner Top From Debris," written by Teller and Sweeney, illustrates such a complex design involving numerous seals for the junk cover. This design requires compensation systems for pressure release and prevention of fluid locks so that the tool can be removed. Additionally, this tool did not address the issue of setting a downhole tool such as a liner packer while blocking entry of debris. It further did not address the need to configure the components in such a way so as to minimize or eliminate damage to the polished bore 22 from the setting or testing operations undertaken before the onset of cementing.
With that background, it is one of the objects of the invention to provide a connection from a setting assembly into a packer-setting sleeve so that debris is kept out while damage to the polished bore is reduced, if not eliminated. It is another object of the invention to provide a simple design which can eliminate the separate junk cover, such as 32, and packer setting assembly 28, and replace them with a simple system which allows for setting the packer 18 while meeting the objectives of elimination of debris and wear on the polished bore, such as 22.